Vulnerable to the same attack as Captchas: paying humans to solve them for a few cents a pop. Cultural factors would probably require training for some of the

Vulnerable to the same attack as Captchas: paying humans to solve them for a few cents a pop. Cultural factors would probably require training for some of the puzzles --- but I don't think that helps much. Someone from the Chinese countryside would probably have about as much luck with the pizza toppings on the first go as I'd have with Chinese ideography, but they'd have it nailed by the tenth.